Information sources may include a variety of structured or unstructured information. An ontology is a type of information source that includes a formal representation of knowledge, which may include a set of concepts within a domain and relationships that exist between those concepts. Ontologies may span diverse fields such as science, history, medicine, geography, etc., without limitation. Examples of ontologies include the DBPEDIA, FREEBASE and GEONAMES ontologies in the Linked Open Data (LOD) cloud, which has presented major advances towards realizing the Semantic Web vision.
Ontologies may be used by applications, such as robust Question Answering (QA) systems, that require many different sources of information. In many instances, these applications attempt to align multiple ontologies to create a large information base. However, often, the alignment of the ontologies is inaccurate and manually intensive. For example, the ontologies may include classes. Alignment of the ontologies may include attempting to correlate the classes in the ontologies with each other. Typically, database experts or knowledge engineers may subjectively view the classes and attempt to correlate them with each other. This process becomes infeasible with ontologies that may be comprised of hundreds or even thousands of classes. Furthermore, subjective alignment may result in inaccurate alignment of classes, which may cause inaccurate or substandard query results.